Thermal fracture and microcarbon separation of coal particles

ABSTRACT

A process for fracturing and devolatilizing coal particles rapidly exposes coal particles to a high temperature, oxygen-depleted work zone for a sufficient time period to cause volatile matter within the coal particles to vaporize and fracture the coal particles. The work zone has a temperature in the range from 600° C. to 2000° C. The coal particles are exposed to the high temperature, oxygen-depleted work zone for a time period less than 1 seconds, and preferably less than 0.3 second. The vaporized volatile matter is condensed and recovered as microcarbon particles.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.16/795,345, filed Feb. 19, 2020, which claims the benefit of U.S.Provisional Application No. 62/807,655, filed Feb. 19, 2019, andentitled THERMAL FRACTURE AND MICROCARBON SEPARATION OF COAL PARTICLES.The prior applications are incorporated by reference.

BACKGROUND OF THE INVENTION

This disclosure relates to rapid thermal fracturing of coal particles.The rapid thermal fracturing also enables a separation of largerparticles and smaller particles, including nano-size and molecular-sizeparticles. The resulting coal particles have a substantially reducedaverage particle size and particle fractions having significantlydifferent carbon (or carbonaceous) and mineral properties.

Traditional coal comminution is done by physical means through variousattrition methods. Coal is milled for different end uses, for examplepulverized coal injection into coal fired power plants or as an additiveto a coking process.

Coal is a natural composite material consisting of carbonaceous matter,entrained mineral matter, and some surface bound and microstructurebound water. Upon combustion of coal, ash is formed from the entrainedmineral matter. The “ash” content of coal refers to the content ofentrained mineral matter in the coal deposit. The carbonaceous matter isbroken down into two further categories: fixed carbon and volatilematter. Volatile matter ranges from less than 10% by mass for anthraciteup to 35% by mass for bituminous coal and as high as 55% by mass or sofor sub-bituminous and lignite coals. The balance of the carbonaceousmass percent is considered to be fixed carbon.

Simply stated, the amount of volatile matter in coal is determined byheating the coal particles to 950° C. in a quartz container with a lidon it and held at 950° C. for 7 minutes. The loss in mass is the percentvolatile matter by mass. (D3175-11—Standard Test Method for VolatileMatter in the Analysis Sample of Coal and Coke.) The bulk of thevolatile matter is coal tar. Coal tar includes macromolecules that havea low enough molecular weight to vaporize at the process temperaturerather than remain as a solid. The lid ensures the coal particles areheated under pyrolytic conditions (absence of oxygen). If oxygen werepresent at the high temperature, the coal particles would burn and beconverted to CO₂.

When heated in the absence of oxygen, e.g. pyrolysis, low molecularweight organic molecules and coal tar starts to enter into the vaporphase at about 200° C. to 250° C. Mass loss above 700° C. is usuallyattributed to carbonization where the coal is becoming pure carbon,losing oxygen, hydrogen, sulfur, and nitrogen, as well as any volatileminor elemental constituents that were bound up within the carbonaceousmatrix.

Molecules entering the vapor phase may have existed as discretemolecules in the carbonaceous matrix. Destructive distillation may occurat just about any temperature, in particular as temperatures exceed 350°C. Destructive distillation is a process by which bond breaking occursto split a larger macromolecule into smaller molecules. These smallermolecules can then enter into the vapor phase. Destructive distillationis usually done in the absence of oxygen. It is a way to break down or“crack” large macromolecules. The organic molecules that enter the vaporphase are generally called “coal tar”. Coal tar is complicated mixtureof polycyclic aromatic hydrocarbons, phenols, and heterocyclic,nitrogen, sulfur, and oxygen compounds. Most coal tar is likely producedvia destructive distillation.

Conventional methods of coal particle size reduction include ballmilling, hammer mill, roller mill, etc. All these methods result inparticles of the same size or reduced size that have the same chemicalcomposition, specifically carbon, nitrogen, oxygen, sulfur, hydrogen,and volatile matter. None of these methods uses heat to reduce particlesize, and none of the methods separate particles by chemical compositionor carbon type. There is currently no effective way to reduce solidparticle size and separate carbon type using heat.

There are two traditional methods for high temperature processing ofcoal. The first process is to burn it for its energy. All four majorgrades of coal (lignite, sub-bituminous, bituminous, and anthracite) areor can be burned. The burning efficiency is reduced with largerparticles size and increased impurities, specifically water, sulfur,nitrogen, oxygen, and mineral matter. Reduction in particles size andremoval of impurities improves the burning efficiency and reducesharmful emissions. The second is to heat it in a coking furnace.Conventional heating processes take minutes or hours and do not resultin reduced particle size. Generally, there is a softening of theparticles followed by a fusion step to produce long range cokestructure. The coking process results in a solid coal-derived material,e.g. coke, with the a uniform chemical composition that is differentfrom the original coal chemical composition. Coal with the “right”properties are used to make coke. Such coals are called metallurgicalgrade coal. These coals are in the mid to high volatile matter range ofbituminous coal and are blended together to make coke. Generally,lignite, sub-bituminous coal, and anthracite cannot be used to make cokeor are used as a very small amount of the coal blend used to make coke.

In a coking furnace, the coal is heated rather slowly. At around 350° C.to 450° C., the coal softens to form a plastic layer which slowlyproceeds throughout the bulk and becomes a very viscous fluid that isoften called “softened coal”. In the temperature range between 400° C.and 500° C., coal tar vapor is separated from the softened coal. As thevapor escapes the softened coal, vacancies, pores, and structure areleft behind in the bulk of the softened coal. Around 450° C. to 550° C.,the softened coal fuses into a solid structure and then begins tocarbonize at higher temperature.

The softening that occurs during the coking process is not an exactmelting event and occurs over minutes or usually hours. The followinghappens during the softening process: low molecular weight materialvaporizes; medium molecular weight material becomes a viscous mass; andlarge molecular weight material undergoes destructive distillation andgives off low molecular weight vapor and medium molecular weightmaterial that combines with the viscous mass. In the softened stage,destructive distillation continues from about 475° C. to 600° C.,resulting in the evolution of tar and aromatic hydrocarbons. Destructivedistillation continues in the melt, causing more material to enter thevapor phase, leaving behind voids and pores in the softened viscousmass. At 600° C. the softened viscous mass begins to transition to asolid via a fusion process that occurs throughout the melt. “The exactmechanism of coal fusion is not completely understood.” (The Chemistryand Technology of Coal p. 224, 2^(nd) Edition). In the solid phase,further destructive distillation occurs, and then carbonizationproceeds. There is still a large amount of volatile matter in the fusedcoal at this point. Destructive distillation continues as temperaturegoes from 600° C. to 1100° C., resulting in further loss in massconsisting of evolved gasses more than just coal tar. Around 1000° C.,hydrogen evolves from the high molecular weight and complex solid tofinalize the carbonization process. The carbonization is complete whenall or most of the hydrogen has been driven off leaving a cokeconsisting almost completely of carbon.

The remaining solid is commonly called coke. Coke is a porous solidmaterial consisting mainly of carbon. One of the main uses of coke is inthe production of iron or steel from iron ore.

In order to optimize the beneficiation of hydrocarbons in coal, theindustry has worked for more than a hundred years on processes toconvert coal to liquid hydrocarbon and coal to gas hydrocarbon. Theseprocesses are inefficient and costly. The typical efficiency ofconverting coal to liquids is on the order of 30% to 35%. The typicalefficiency of converting coal to gas is 50% efficiency. In contrast, thetypical efficiency of converting coal to solids using the processesdisclosed herein is 75% to 90%. In other words, starting with 100 tonsof dry coal feedstock, coal to liquid processes may yield up with 30tons to 35 tons of liquid. Coal to gas processes may yield up with 50tons of gas. While coal to solids as disclosed herein may yield from 75to 90 tons of solids.

There is a need in the art for a process for converting coal to usefulsolids. Processes to convert coal to solids are set forth in thisdisclosure.

An advantage of converting coal to liquid and coal to gas is that theyare beneficiation processes for the removal of impurities. There is aneed in the art for an efficient coal-to-solid beneficiating process forthe removal of impurities.

Producing a solid product allows for all the advantages of solidshandling and solids transport.

SUMMARY OF THE INVENTION

This disclosure relates to rapid or instantaneous thermal fracturing ofcoal as a new way to rapidly reduce coal particles size. The process canalso separate volatile matter from coal particles without substantiallyreducing the total carbon mass in the volatile matter. It can alsoreduce or eliminate impurities, including, but not limited to, sulfur,nitrogen, phosphorous, etc. In the thermal fracture process, an enclosedwork zone with an oxygen depleted gas is heated to approximately 1000°C. or a range from about 600° C. to 2000° C., preferably in the range of600° C. to 1500° C. A work zone temperature from about 400° C. to 600°C. is useful for rapid production of coal. A work zone temperature fromabout 600° C. to 800° C. for producing microcarbon particles with highoxygen content that are non-conductive. A work zone temperature fromabout 1000° C. to 2000° C. is useful for production of microcarbonparticles that are conductive and that resemble carbon black.

At temperatures greater than 1000° C., the commercial industry convertsa substantial portion of the mass to liquids and/or gases. The disclosedprocess conserves the majority of the carbon mass as a solid. This hasadvantages for transportation and handling. The products produced inthis new process are novel and of significant value.

Coal particles are pneumatically conveyed through this high temperaturezone. The coal particles that are fed into the process can be less than10 mm in size. In another instance, the coal particles that are fed intothe process can be less than 6 mm in size. In another instance, the coalparticles that are fed into the process were between 0.3 mm and 1 mm. Inanother instance, the coal particles that are fed into the process canbe less than 0.5 mm in size. In another instance, the coal particlesthat are fed into the process can be less than 0.2 mm in size.

Retention time of the coal particles within the high temperature zone isusually less than 1 second, and often less than 0.02 seconds, and attimes less than 0.3 seconds, and sometimes less than 0.1 seconds. Theinstantaneous thermal shock on the individual coal particles causesorganic molecules having different molecular weights and vaporizationtemperatures to expand rapidly causing a de-stabilization and fracturingof the original coal particles into smaller sizes.

The resulting fractured coal-derived particles have an average particlesize less than 200 μm. In some non-limiting embodiments, the averageparticle size is less than 100 μm. The average size of the fractured andlow volatile matter particles is usually between 40 μm and 100 μm.

The disclosed process may produce coal-derived microcarbon particleswith a diameter less than 1 mm. The disclosed process may producecoal-derived microcarbon particles with a diameter less than 0.5 mm. Thedisclosed process may produce coal-derived microcarbon particles with adiameter less than 0.2 mm.

The disclosed process may produce coal-derived microcarbon particleswith volatile matter less than 10% by weight. The disclosed process mayproduce coal-derived microcarbon particles with volatile matter lessthan 3% by weight.

The disclosed process may produce coal-derived microcarbon particleswith a carbon content greater than 90% by weight. The disclosed processmay produce coal-derived microcarbon particles with a carbon contentgreater than 95% by weight.

The disclosed process may produce coal-derived microcarbon particleswith a sulfur content less than 1% by weight. The disclosed process mayproduce coal-derived microcarbon particles with a sulfur content lessthan 0.5% by weight.

The disclosed process may produce coal-derived microcarbon particleswith a nitrogen content less than 1.5% by weight. The disclosed processmay produce coal-derived microcarbon particles with a nitrogen contentless than 1% by weight. The disclosed process may produce coal-derivedmicrocarbon particles with a nitrogen content less than 0.7% by weight.The disclosed process may produce coal-derived microcarbon particleswith a nitrogen content less than 0.5% by weight.

The disclosed process may produce coal-derived microcarbon particleswith an ash content less 1% by weight. The disclosed process may producecoal-derived microcarbon particles with an ash content less 0.5% byweight. The disclosed process may produce coal-derived microcarbonparticles with an ash content less 0.1% by weight.

The disclosed process may produce coal-derived microcarbon particlesthat are electrically conductive.

The disclosed process may produce coal-derived microcarbon particlesthat have a diameter less than 1 mm, volatile matter less than 10% byweight, carbon content greater than 90% by weight, sulfur less than 1%by weight, and nitrogen less than 1% weight, and ash content less 1% byweight.

The disclosed process may produce coal-derived low volatile matter andfractured particles with a porous surface with a diameter that is 5times or more smaller than the original coal particles, volatile matterless than 10% by weight, carbon content greater than 90% by weight,sulfur less than 1% by weight, and nitrogen less than 1.5% by weight.

The disclosed process may produce a blend of coal-derived microcarbonparticles and coal-derived low volatile matter and fractured particles.The coal-derived microcarbon particles and coal-derived low volatilematter and fractured particles may have a volatile matter content lessthan 10% by weight. The coal-derived microcarbon particles andcoal-derived low volatile matter and fractured particles may have acarbon content greater than 90% by weight. The coal-derived microcarbonparticles and coal-derived low volatile matter and fractured particlesmay have a sulfur content less than 1% by weight. The coal-derivedmicrocarbon particles and coal-derived low volatile matter and fracturedparticles may have a nitrogen content less than 1.5% by weight.

The disclosed process may produce a blend of coal-derived microcarbonparticles and coal-derived low volatile matter and fractured particles,with greater than 5% coal-derived microcarbon particles. The disclosedprocess may produce a blend of coal-derived microcarbon particles andcoal-derived low volatile matter and fractured particles, with greaterthan 5% low volatile matter and fractured particles.

The disclosed process may include an enclosed work zone with anoxygen-depleted atmosphere having an oxygen content less than 5% byweight. The disclosed process may include an enclosed work zone with anoxygen-depleted atmosphere having an oxygen content less than 1% byweight. The disclosed process may include an enclosed work zone with anoxygen-depleted atmosphere having an oxygen content less than 0.5% byweight.

The disclosed process may include a work zone having a temperaturegreater than 1000° C. The disclosed process may include a work zonehaving a temperature greater than 1200° C. The disclosed process mayinclude a work zone having a temperature greater than 1400° C. Thedisclosed process may include a work zone having a temperature greaterthan 1600° C.

The disclosed process may include a work zone and the coal particleshave a residence time in the work zone less than 2 seconds. Thedisclosed process may include a work zone and the coal particles have aresidence time in the work zone less than 1 second.

The disclosed process may form low volatile matter and fracturedparticles and microcarbon particles simultaneously in the same hightemperature work zone.

The disclosed process may include an enclosed work zone with anoxygen-depleted atmosphere having an oxygen content less than 5% byweight, a temperature greater than 1000° C., a coal particle residencetime in the work zone less than 2 seconds, resulting in simultaneousformation of low volatile matter and fractured particles and microcarbonparticles at the same time in the same high temperature work zone.

In one aspect of the disclosed process, unprocessed coal particleshaving a given sulfur content are processed in an oxygen depleted gas ata temperature greater than 1200° C. to produce a coal-derived materialhaving a sulfur content that is less than 50% of the sulfur content ofthe unprocessed coal.

In one aspect of the disclosed process, unprocessed coal particleshaving a sulfur content greater than 1.5% by weight are processed in anoxygen depleted gas at a temperature greater than 1200° C. to produce acoal-derived material having a sulfur content that is less than 0.8% byweight.

In one aspect of the disclosed process, unprocessed coal particleshaving a sulfur content greater than 1% by weight are processed in anoxygen depleted gas at a temperature greater than 1200° C. to produce acoal-derived material having a sulfur content that is less than 0.5% byweight.

In one aspect of the disclosed process, unprocessed coal particleshaving a given volatile matter content are processed in an oxygendepleted gas at a temperature greater than 1200° C. to produce acoal-derived material having a volatile matter content that is less than5% by weight.

In one aspect of the disclosed process, unprocessed coal particleshaving a given particle size are processed in an oxygen depleted gas ata temperature greater than 1200° C. for less than 1 second to produce acoal-derived material having an average particle size that is less than50% of the particle size of the unprocessed coal particles.

The disclosed process also includes further processing of the vaporizedvolatile matter. This includes different techniques for condensing oragglomerating the vaporized volatile matter. The disclosed process alsoincludes formation and recovery of carbon and microcarbon.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed. It is understood thatspecific aspects and features of the disclosed invention may be freelycombined with other specific aspects and features of the disclosedinvention. It should be understood that the various embodiments are notlimited to the arrangements and instrumentality shown in the drawings.It should also be understood that the embodiments may be combined, orthat other embodiments may be utilized and that structural changes,unless so claimed, may be made without departing from the scope of thevarious embodiments of the present invention. The following detaileddescription is, therefore, not to be taken in a limiting sense.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In order that the manner in which the above-recited and other featuresand advantages of the invention are obtained will be readily understood,a more particular description of the invention briefly described abovewill be rendered by reference to specific embodiments thereof that areillustrated in the appended drawings. Understanding that these drawingsdepict only typical embodiments of the invention and are not thereforeto be considered to be limiting of its scope, the invention will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

FIG. 1 shows a graph of particle size analysis for feed material coalparticles.

FIG. 2 shows a graph of particle size analysis for the thermal fracturedcoal-derived particles according to the disclosed process.

FIG. 3 shows an SEM image of microcarbon particles formed during rapidthermal fracture of the coal particles at about 1200° C. with aresidence time of 1 second.

FIG. 4A and FIG. 4B show SEM images of microcarbon particles formedduring rapid thermal fracture of the coal particles at about 1000° C.with a residence time of 0.4 seconds.

FIG. 5 shows an SEM image of microcarbon particles formed during rapidthermal fracture of the coal particles at about 900° C. with a residencetime of 2 seconds.

FIG. 6 shows an SEM image of low volatile matter and fractured particlesformed during rapid thermal fracture of the coal particles at about1000° C. with a residence time of 0.4 seconds.

FIG. 7 shows an SEM image of low volatile matter and fractured particlesformed during rapid thermal fracture of the coal particles at about 600°C. with a residence time of 0.2 seconds.

FIG. 8 shows an SEM image of the 1 mm×0.3 mm coal feed particles.

FIGS. 9-13 are block diagrams showing thermal mill and microcarbonseparation systems.

FIG. 14 shows a graph of maximum dimension of microcarbon particles as afunction of work zone temperature.

FIG. 15 shows a graph of the average particle size of the low volatilematter and fractured particles as a function of work zone temperaturefor three different coal particle sizes used as a feed material for theprocess.

FIG. 16 shows a graph of wt. % volatile matter of low volatile matterand fractured particles as a function of work zone temperature whenusing bituminous coal, sub-bituminous coal, or lignite coal for theprocess.

DESCRIPTION OF THE INVENTION

This disclosure relates to rapid thermal fracturing of preferably drycoal particles and the formation of microcarbon particles. The moistureis usually less than 5 wt. %. Preferably the moisture content is lessthan 2%. Most preferably, the moisture approaches 0%. The rapid thermalfracturing also enables a separation of larger particles and smallerparticles, including nano-size and molecular-size particles. Theresulting coal-derived particles have a substantially reduced averageparticle size and particle fractions having significantly differentcarbon (or carbonaceous) and mineral properties.

As stated above, the volatile matter in coal typically ranges from lessthan 10% by mass up to about 55% by mass across the different coalranks. The volatile matter is uniformly distributed throughout the coalparticles as evidenced by fine coal particles (less than 100 μm) andlarge coal rocks from the same source having the same volatile mattercontent. As disclosed herein, when the volatile matter or coal tar thatis dispersed evenly throughout the coal particle flash vaporizes, thecoal particle shatters or fractures into multiple pieces. The resultingparticles include the fixed carbon (free of coal tar) portion of thecarbonaceous matter of coal.

Dry Coal particles are pneumatically fed into a high temperature andoxygen depleted work zone. The coal particles are less than 5% moisture,less than 2% moisture, preferably less than 1% moisture. Oxygen istypically less than 1.5%, preferably less than 1%, and even morepreferably less than 0.5%. The residence time in the work zone is lessthan 5 seconds. In some non-limiting embodiments, the residence time inthe work zone is less than 1 second, and often less than 0.4 seconds.Often the residence time is less than 0.2 seconds. The coal particlesare heated almost instantly to a temperature greater than about 400° C.causing low molecular weight coal tar to vaporize instantaneously. Asthe coal tar expands rapidly, the coal particle breaks or fractures intosmaller pieces, with an average size less than 200 μm in diameter. Insome cases, the average size of the fractured coal-derived particles isless than 100 μm in diameter.

These smaller particles are called low volatile matter and fracturedparticles. The low volatile matter and fractured particles exit the hightemperature work zone via pneumatic conveyance and enter into a cyclone.The low volatile matter and fractured particles are collected from theunderflow of the cyclone. The standard method for measuring volatilematter for coal shows them to have less than 10% volatile matter,usually about 8%. The low volatile matter and fractured particles aredifferent from the feed coal in size, and volatile matter, and maydiffer in carbon (C), hydrogen (H), nitrogen (N), sulfur (S), and oxygen(O) content depending on the temperature of the work zone. In fact, thevolatile matter that remains consists largely of H, N, S, and O in thecarbonaceous matrix that would be driven off during high temperaturecarbonization as well as some organic compound that are lost due tocontinuing destructive distillation, most likely methane ethane,propane, or butane.

The coal tar vapor exits the top of the cyclone with the hightemperature oxygen depleted gas stream.

When flash devolatization and thermal fracture of the coal particlesoccurs at lower temperatures, between about 400° C. and 800° C., thecoal tar vapor can be condensed into a viscous liquid state afterexiting the cyclone. This coal tar can then be used in processes andproducts that use coal tar. When flash devolatization and thermalfracture of the coal particles occurs at higher temperatures, greaterthan 600° C., more preferably above 850° C., even more preferably above1000° C., even more preferably above 1200° C., the organic hydrocarbongasses (methane, ethane, propane, butane, etc.) that may be present andthe larger polycyclic organic molecules called coal tar vapor that maybe present undergo further destructive distillation and carbonization inthe vapor phase. The product of this process are agglomerates ofgraphite layers that form spheres on the order of 10 to 500 nm indiameter. The spheres can also be connected together to form long rangestructure. The connection can be chemical or intra-particle forces suchas surface energy minimization or van der Waals forces.

Example 1

Sieve analysis was done on the coal particle feed material. Particlesize analysis was also done on the material. More than 99% of the massof the material was greater than 0.355 mm. The material is mixed for ashort period 5 seconds with a handheld high-speed mixer in the presenceof a non-ionic surfactant to ensure all the particles are separated.Particle size analysis was conducted using a laser diffraction particlesize analyzer. The particles have a peak particle size at about 0.5 mm.The average is 0.51 mm with a d97 of 0.795 mm. d97 means that 97% of theparticles have a diameter smaller than the size given. The sieveanalysis results are reported in Table 1 and the results from theparticle size analyzer are shown in FIG. 1 .

TABLE 1 Retained Mass Sieve + on Sieve Material Mass Sieve Mass Material(mm) (g) (g) (g) wt. % 1.180 419.16 416.04 3.12 1.48 1.000 418.08 395.4022.68 10.77 0.600 504.40 386.81 117.59 55.84 0.500 410.04 366.48 43.5620.68 0.355 371.61 349.43 22.18 10.53 0.250 338.62 337.87 0.75 0.360.075 314.32 313.74 0.58 0.28 Pass 365.37 365.24 0.13 0.06 Total 210.59100.00

Example 2

Sieve analysis was done on the low volatile matter and fracturedparticles. About 70% of the mass of the material was less than 0.5 mm.In order to get a better understanding of the fractured particle size,particle size analysis was also done on the material using a laserdiffraction particle size analyzer. The material was mixed for 10 secondwith a high-speed hand mixer in the presence of a non-ionic surfactantto ensure all the particles are separated. The particles have a peakparticle size at about 0.06 mm. The average is 0.058 mm with a d97 of0.135 mm. The sieve analysis results are reported in Table 2 and theresults from the particle size analyzer are shown in FIG. 2 .

The individual particles produced via thermal fracture conditions aresmaller than the feed particle to the thermal fracture process. Theaverage particle size diameter for the thermal fracture particles wasreduced by nearly a factor of 10 in this example.

TABLE 2 Retained Mass Sieve + on Sieve Material Mass Sieve Mass Material(mm) (g) (g) (g) wt. % 1.180 417.66 416.04 1.62 1.84 1.000 398.71 395.403.31 3.77 0.600 402.06 386.81 15.25 17.37 0.500 372.92 366.48 6.44 7.330.355 361.78 349.43 12.35 14.06 0.250 349.67 337.87 11.80 13.44 0.075339.13 313.74 25.39 28.91 Pass 376.89 365.24 11.65 13.27 Total 87.81100.00

Example 3

The volatile matter of the feed coal particles was measured to be about33.7%. The feedstock was Pittsburgh 8 coal. Pittsburgh 8 coal is a highvolatile matter metallurgical grade coal, meaning in the coking process,it will soften, swell during coal tar evolution, and then fuse togetherto form the porous long range coke structure.

After the Pittsburgh 8 coal is used as the feedstock in the rapidthermal fracture and microcarbon separation process described above, thevolatile matter of the fractured coal-derived particles ranged between6% and 9% by mass using a work zone temperature of 1000° C. and aretention time in the work zone of 0.6 seconds.

It is believed that the coal feed particles heat up so quickly in therapid thermal fracture process described herein that the fractured solidparticles produced in the process do not pass through a softening stageand fusion step as in the case in the much slower coking process. Thefractured particles that remain are solid. The rapid heating eventcauses instantaneous vaporization of the organic gasses and coal tar viaboth vaporization and destructive distillation and vaporization.

Stated otherwise, it is believed that the coal particles do not enter amelt stage from which much of the coal tar and organic gasses evolve asin the coking process. The rapid heating causes instantaneousvaporization of existing coal tar molecules and destructive distillationand vaporization of organic gasses and coal tar molecules from the solidparticles. The rapid vaporization fractures the coal particles as theorganic gases and coal tar vapor evolve. This event is calledinstantaneous or immediate vaporization and fracture because it canhappen in less than 2 seconds, in less than 1 second, in less than 0.4seconds, and in less than 0.2 seconds.

It is believed that the solid particles that remain, called low volatilematter and fractured particles herein, did not soften as in the cokingprocess because they were heated through this temperature range soquickly. Instead, it is believed that they preceded directly to thefusion stage that is often described in the coking process. If theparticles remain in the high temperature work zone for longer periods oftime, destructive distillation can continue to remove organic gasses andcoal tars to the gas and vapor phase from the solid particle mass.Carbonization at temperatures above about 850° C., more preferably above1000° C. and even more preferably above 1200° C., will liberate H, N, S,and O from the carbonaceous matrix. If carbonized long enough, theseparticles will reach a high carbon content. The carbon content canexceed 90% on an ash free basis.

Example 4

The volatile matter can be recovered and utilized in different ways. Onepossible use for the volatile matter would be to condense it and sell itinto the existing organic gasses and coal tar market. A second would beto direct the volatile matter towards a combustor and burn it for heat.A third possible use for the volatile matter would be to further processit through distillation, cracking, coal to gas, coal to liquid, or othersimilar downstream processing.

Example 5

Another way to utilize the organic gases and coal tar vapor is toconvert it directly to microcarbon particles similar in nature to carbonblack from the vapor phase. When rapid thermal fracture of the coalparticles occurs at higher temperatures, greater than about 800° C., thecoal tar vapor carbonizes in the vapor phase. When a carbonized coalvapor reaches a sufficiently large size, it exits the vapor phase assolid particles, called microcarbon particles in this disclosure.

A similar material to microcarbon particles is carbon black. Microcarbonparticles are not produced in the same manner in which carbon black istraditionally produced. Carbon black production is described by partialcombustion and thermal decomposition of the feedstock (propane,acetylene, petroleum oils, coal oils, coal tars, etc.) in a hot oxygendepleted gas stream. In the case of the thermal fracture and microcarbonparticle production, a coal feedstock is injected directly into anoxygen deprived, high temperature gas stream where the gas stream isless than 1% oxygen, preferably less than 0.5% oxygen, even morepreferably less than 0.1% oxygen.

One method of producing a high temperature and oxygen deprived gas isthe combustion gas exiting a pulse combustor or pulse jet engine. Thepulse combustor can use propane, natural gas, fine coal particles lessthan 50 microns in diameter or some mixture thereof as the fuel. Anothermethod is a standard combustor using propane or natural gas. Anothermethod is a standard combustor for pulverized coal. Another method isflowing oxygen deprived gas over heating elements and/or heat exchangersthat are heated by electricity or burning solid, liquid, or gaseousfuel.

Under these conditions, the feedstock coal particles begin to undergopyrolysis immediately upon injection into the hot and oxygen deprivedgas stream. There is negligible partial combustion of the coal particlesor emanating organic gasses and coal tar vapor because there is nooxygen. Instead, pyrolysis happens immediately in the hot and oxygendepleted gas stream. As already described, the organic gasses and coaltar vapors are instantly vaporized through vaporization and destructivedistillation and subsequent vaporization. The organic gasses and coaltar vapor then undergo further carbonization and nucleate to form stableand solid microcarbon particles, e.g., carbon black or carbon black-likeparticles, that exit the vapor phase and are pneumatically conveyedthrough and out of the work zone. These new particles represent a massfraction up to 10% to 75% of the initial coal feedstock mass dependingon the volatile matter content of the feed coal particles, thetemperature at which the process is run, and the residence time in theprocess. The microcarbon particles have a new morphology, chemicalmakeup and mineral properties compared to the original coal particles aswell as organic gases or coal tars from which they were made

Without being bound by theory, upon near-instantaneous vaporization ofcoal tars when the coal particles are pneumatically conveyed into theoxygen deprived work zone at 1000° C., the coal tar temperature quicklyheat up to reach 1000° C. At this high temperature the organic gases andcoal tar vapor in the oxygen depleted gas stream begin to carbonize.This means the carbon molecules lose hydrogen, oxygen, nitrogen, sulfur,and any other minor constituents creating molecules of nearly purecarbon that have a graphite-like structure. The layers aggregatetogether until their molecular mass is such that they cannot exist inthe vapor phase. At this point, they exit from the vapor phase as amicrocarbon particle

The microcarbon particle product has morphology, chemistry, andconductivity traditionally associated with carbon black when produced attemperatures in excess of about 1000° C. When produced at temperaturesbetween about 800° C. and 1000° C., the microcarbon particles producedfrom the organic gasses and coal tar vapor differ from carbon black inmorphology and chemistry.

FIG. 3 shows an SEM of microcarbon particles formed in this manner. Thisparticle was made with a work zone temperature of 1200° C. and aresidence time of 2 seconds. The spherical structure seen in the SEM isrepresentative of carbon black morphology. These microcarbon particleswere conductive. The spheres have a diameter range of about 20 to 44 nm.Volatile matter was about 1.2%. Carbon (C), hydrogen (H), nitrogen (N),sulfur (S), and oxygen (O) (CHNSO) analysis was done with a CHNSOElemental Analyzer. Oxygen was obtained by difference. CHNSO values arereported on ash-free basis. Oxygen content was about 1.15%. CHNSO datais shown in Table 3. The low CHNSO values and conductivity of thematerial indicate that carbonization was reaching completion, producingnearly pure carbon. The carbon content of about 96%.

FIGS. 4A and 4B shows SEM images for microcarbon particles produced atabout 1000° C. and a residence time of 0.4 seconds. There are flatcircular structures along with somewhat larger flat structures. Thereare also some spherical structures as were observed in FIG. 3 . Themicrocarbon particles in FIGS. 4A and 4B are produced at a temperaturebetween those used to produce the microcarbon particles shown in FIG. 3and FIG. 5 . The microcarbon particles in FIG. 4 appear to be a blend ofthe two structure sets shown in FIGS. 3 and 5 that were produced athigher and lower operation temperatures respectively. The spheres have adiameter range of about 44 to 90 nm. Volatile matter was about 8.1%.CHNSO data is shown in Table 3. Oxygen content in CHNSO analysis wasabout 6.4%.

FIG. 5 shows an SEM image for microcarbon particles produced at about900° C. and a residence time of 2 seconds. Flat long-range structure isobserved for this low temperature operation (<1000° C.). The structuredimensions range from about 130 to 550 nm. Volatile matter was about9.0%. CHNSO data is shown in Table 3. Oxygen content in CHNSO analysiswas about 9.4%.

FIG. 6 shows an SEM image for fractured and low volatile matterparticles produced at about 1000° C. and a residence time of 0.4seconds. The fractured structure can be observed. All of the particlesappear to be below 100 μm. The particles were conductive. Volatilematter was about 1.8%. CHNSO data is shown in Table 3. Oxygen content inCHNSO analysis was about 1.77%. The low CHNSO values and conductivity ofthe material indicate that carbonization was reaching completion,producing nearly pure carbon. The carbon content was about 95%.

FIG. 7 shows an SEM image for fractured and low volatile matterparticles produced at about 600° C. and a residence time of 0.2 seconds.The fractured structure can be observed. All of the particles appear tobe below 100 μm. Volatile matter was about 8.2%. CHNSO data is shown inTable 3. Oxygen content in CHNSO analysis was about 9.2%.

FIG. 8 shows an SEM image of the 1 mm×0.3 mm coal feedstock into thethermal fraction and microcarbon separation process. The coal particlefeedstock had smooth, flat surfaces without the pore structure seen inthe low volatile matter and fractured particles.

Example 6

TABLE 3 Temperature Residence Volatile when Feed was Time Matter AshFree Values Type of Particle Started (° C.) (seconds) (wt. %) ConductiveC % H % N % O % S % Microcarbon particles 1,600 0.4 1.13% Yes 98.91 0.110.08 0.62 0.28 Microcarbon particles 1,400 0.6 1.71% Yes 98.42 0.18 0.120.87 0.41 FIG. 3 Microcarbon 1,200 1 2.62% Yes 97.53 0.30 0.19 1.15 0.83particles FIG. 4 Microcarbon 1,000 1.5 8.12% No 89.72 0.42 1.61 6.391.86 particles FIG. 5 Microcarbon 900 2 9.03% No 86.48 1.15 1.13 9.421.82 particles Low volatile matter and 1,600 0.4 1.52% Yes 98.59 0.150.62 0.33 0.31 fractured particles Low volatile matter and 1,400 0.61.87% Yes 97.50 0.21 0.94 0.63 0.72 fractured particles Low volatilematter and 1,200 1 3.85% Yes 96.32 0.36 1.32 1.03 0.97 fracturedparticles FIG. 6 Low volatile matter 1,000 1.5 5.28% No 95.07 0.58 1.771.45 1.14 and fractured particles FIG. 7 Low volatile matter 600 2 8.24%No 85.20 2.83 1.18 9.20 1.59 and fractured particles FIG. 8 Coal Feedmaterial — — 33.5% No 80.78 5.24 1.74 10.15 2.09 1 mm × 0.3 mm

Table 3 above shows the conductivity and CHNSO characterization resultsfor microcarbon particles and low volatile matter and fracturedparticles produced from a 1 mm×0.3 mm bituminous coal particles. Thecharacterization of the 1 mm×0.3 mm coal particles are also shown. SEMimages of some of the different particles for which data is given inTable 3 are shown in FIG. 3 to FIG. 8 . Conductivity was determined byinserting the probes of a multimeter into dry powder of the givenparticles. If a resistance was measured, then the particles wereconsidered to be conductive. Conductivity is 1/resistivity. Percentagesfor each element are % by mass.

The microcarbon particles and the low volatile matter and fracturedparticles produced above 1000° C. had carbon content greater than 95%,low oxygen content (<1.5%) content and were conductive. The microcarbonparticles and the low volatile matter and fractured particles producedbelow 1000° C. had higher oxygen content (5%) content and were notconductive. It would appear that oxygen contents much greater than 1.5%cause the particles to not be conductive. Final carbonization where H,N, O, and S are removed from the molecular organic structure that makesup the particles occurs more rapidly and more completely as temperatureincreases. The reaction time was not long enough for carbonization todrive off enough oxygen from the carbonaceous matrix for the microcarbonparticle or for the low volatile matter and fractured particles producedat 900° C.

Further tests were done where the work zone was 1200° C., 1400° C., and1600° C. As the temperature in the work zone increased, furthercarbonization occurred in the same period of time.

At 1200° C. in the work zone, volatile matter a was less than 2.7%,nitrogen was less than 0.2%, sulfur was less than 0.9%, and carbon wasgreater than 96.5% for the microcarbon particles. At 1200° C. in thework zone, volatile matter was less than 3.9%, nitrogen was less than1.4%, sulfur was less than 1.0%, and carbon was greater than 96.3% forthe low volatile matter and fractured particles.

At 1400° C. in the work zone, volatile matter a was less than 1.8%,nitrogen was less than 0.15%, sulfur was less than 0.5%, and carbon wasgreater than 98.4% for the microcarbon particles. At 1400° C. in thework zone, volatile matter was less than 1.9%, nitrogen was less than1.0%, sulfur was less than 0.8%, and carbon was greater than 97.4% forthe low volatile matter and fractured particles.

At 1600° C. in the work zone, volatile matter a was less than 1.2%,nitrogen was less than 0.1%, sulfur was less than 0.3%, and carbon wasgreater than 98.9% for the microcarbon particles. At 1600° C. in thework zone, volatile matter was less than 1.6%, nitrogen was less than0.7%, sulfur was less than 0.4%, and carbon was greater than 98.5% forthe low volatile matter and fractured particles.

Thermal Mill and Microparticle Separator

The disclosed process for the rapid thermal fracturing of coal particlesand the rapid devolatilization of volatile matter within coal particlesmay occur in a thermal mill apparatus, one non-limiting example of whichis shown schematically in FIGS. 9, 10, 11, and 12 . The thermal mill 100includes a work zone 110. The work zone 110 has an oxygen-depleted gasheated to a temperature of approximately 600° C. to 2000° C., usually ina range from about 600° C. to 1300° C. A source of high temperature,oxygen-depleted gas 120 is connected to the work zone 110 to provide thework zone with its operating temperature and gas conditions. The workzone has a coal particle inlet 130 and a fractured particle outlet 140.

A source of oxygen depleted high speed gas 150, where high speed means agas of sufficient velocity and mass flow to convey coal particlesintroduced into the oxygen depleted gas, entrains and conveys a coalparticle feed stream 160 via the coal particle inlet 130 into the workzone 110. The coal particles may have a particle size less than 4 mm.The coal particles are exposed to the high temperature oxygen depletedgas of the work zone for a sufficient time period to cause volatilematter within the coal particles to vaporize and fracture the coalparticles, thereby forming fractured coal-derived particles. The coalparticles are exposed to the work zone for a time period less than 2seconds, and often less than 1 second. In currently preferredembodiments, the coal particle residence time is less than 0.4 secondsand less than 0.2 seconds. In another embodiment, the residence time inthe work zone is less than 0.6 seconds. The rapid, near instantaneousexposure to the high temperature work zone causes the volatile matterdispersed throughout the coal particles to flash vaporize and to shatteror fracture the coal particle into multiple pieces of fracturedparticles. The resulting coal particles have a substantially reducedparticle size, increased porosity, and decreased volatile mattertherein. The fractured particles may have an average particle size lessthan 200 μm, and often less than 100 μm.

The fractured particles remain entrained within the stream of oxygendepleted high speed gas and are conveyed from the work zone to a productcollection system 170 via the fractured particle outlet 140.

One non-limiting example of the product collection system 170 is thecyclone collector described herein.

FIG. 10 shows the lower temperature process regime from about 400° C. to800° C. Higher oxygen content and non-conductive low volatile matter andfractured particles are produced via rapid thermal fracture in the workzone, then exit the underflow of the cyclone to be collected. Coal tarvapor exits the top of the cyclone and is collected, for example in acondenser. Ash content of the coal tar is less than 1%. The low volatilematter and fractured particles had an ash content of about 15% and avolatile matter of ranging from 10% to 16%. Depending on the volatilematter of the coal particles (bituminous, sub-bituminous, lignite,anthracite) about 60% to 80% was of the mass of the coal particles wasconverted to low volatile matter and fractured particles. About 20% to40% of the mass of the coal particles was converted to coal tar.

FIG. 11 shows the middle temperature process regime from about 800° C.to about 1000° C. Higher oxygen content and non-conductive low volatilematter and fractured particles are produced via rapid thermal fracturein the work zone, then exit the underflow of the cyclone to becollected. Higher oxygen content and non-conductive microcarbonparticles exit the top of the cyclone and are collected, for example ina baghouse. Depending on the volatile matter of the coal particles(bituminous, sub-bituminous, lignite, anthracite), about 55% to 75% ofthe mass of the coal particles was converted to low volatile matter andfractured particles. About 25% to 45% of the mass of the coal particleswere converted to microcarbon particles. Ash content of the microcarbonparticle was less than 1%, volatile matter was about 9%, oxygen contentwas about 9.4%, and the particles were non-conductive. Ash content ofthe low volatile matter and fractured particles was about 20%, volatilematter was about 9% to 12%, oxygen content was about 6.4%, and theparticles were non-conductive.

FIG. 12 shows the high temperature process regime with work zonetemperatures greater than 1200° C., preferably between about 1200° C.and 1400° C. Temperatures as high as 2000° C. can be used in the workzone. In the work zone, the organic gasses and coal tar vapor producedduring thermal fracture immediately undergo further destructivedistillation and carbonization to produce microcarbon particles withspherical structure. Depending on temperature and residence time, thespheres can be individual or agglomerated. Often the agglomerates arephysically attached spheres to form chains and branched chains ofspheres to create longer range structures of the spheres. The individualspheres or connected spheres form longer range structure commonly calledcarbon black. As temperature increases and residence time decreases, thediameter of the microcarbon spheres decreases. Smaller diametermicrocarbon spheres are generally considered of higher value incommercial markets. Lower oxygen content and conductive low volatilematter and fractured particles are produced via rapid thermal fracturein the work zone, then exit the underflow of the cyclone to becollected. Lower oxygen content and conductive microcarbon particlesexit the top of the cyclone and are collected, for example in abaghouse. Depending on the volatile matter of the coal particles(bituminous, sub-bituminous, lignite, anthracite), about 45% to 65% ofthe mass of the coal particles was converted to low volatile matter andfractured particles. About 35% to 65% of the mass of the coal particleswere converted to microcarbon particles. Ash content of the microcarbonparticle was less than 1%, volatile matter was less than 2%, oxygencontent was low, and the particle was conductive. Ash content of the lowvolatile matter and fractured particles was about 28.5%, volatile was0.5% to 5% and the particle was conductive.

Another Thermal Mill and Microparticle Separator Design

Another embodiment of the thermal mill and microcarbon separationprocess is shown in FIG. 13 . This embodiment has a two work zones setat two different temperatures. The temperature in both zones can be setat any temperature within the preferred temperature range of 600° C. to2000° C. The preferred embodiment has the first work zone temperatureset between 600° C. and 800° C. In another embodiment, the temperatureof the first work zone may be set as low as 400° C. Under theseconditions, rapid thermal fracture occurs. Approximately 65% to 75% ofthe coal particles, based on work zone temperature, becomes low volatilematter and fractured particles that are about 20% ash and 9% volatilematter, and about 6 to 10% oxygen. The remainder of the feedstock massis in the form of organic gasses and coal tar vapor. The organic gassesand coal tar vapor exit the top of the cyclone and enter into the secondwork zone. The second work zone is set at a temperature greater than1000° C., preferably between about 1200° C. and 1400° C. Temperatures ashigh as 2000° C. can be used in the second work zone, however. In thesecond work zone, the organic gasses and coal tar vapor undergo furtherdestructive distillation and carbonization to produce microcarbonparticles with spherical structure. Depending on temperature andresidence time, the spheres can be individual or agglomerated. Often theagglomerates are physically attached spheres to form chains and branchedchains of spheres to create longer range structures of the spheres. Theindividual spheres or connected spheres form longer range structurecommonly called carbon black. As temperature increases and residencetime decreases, the diameter of the microcarbon spheres decreases.Smaller diameter microcarbon spheres are generally considered of highervalue in commercial markets. Low volatile matter and fractured particlesare produced via rapid thermal fracture in the work zone and exit thebottom of the cyclone and are collected. Microcarbon particles exits thetop of the cyclone and are collected, for example in a baghouse.

Example 7

TABLE 4 Work Zone Maximum Dimension of Temperature Microcarbon Particles(° C.) (μm) 600 1 800 0.5 1000 0.15 1200 0.045 1400 0.025 1600 0.02 20000.015

Table 4 above shows the maximum dimension of microcarbon particles as afunction of work zone temperature. FIG. 14 shows this data as a graph.

The maximum dimension of microcarbon particles is shown to decreaserapidly as a function of temperature until starting to reach a lowerlimit at 2000° C. As temperatures exceed about 800° C. to 1000° C., themicrocarbon structure is predominantly spherical. Below 800° C. themicrocarbon particles have a more long-range flat structure. The longdimension can be as large as 1 μm. The shorter dimension may only beabout 0.2 μm for a maximum dimension of 1 μm. The data shown in Table 4and FIG. 14 were collected for microcarbon particles made using 35 wt. %volatile matter bituminous coal as the feed material for the thermalfraction and microcarbon separation process. Microcarbon particles madefrom feedstocks of lignite, bituminous, sub-bituminous, and anthraciteall showed similar particle size trends for the temperature range shownabove.

Example 7

TABLE 5 Work Zone 0.3 mm to Less than Less than Temperature 1 mm Coal 5mm Coal 10 mm Coal (° C.) Particles Particles Particles 600 350 10002000 800 200 260 500 1000 75 100 200 1200 50 53 55 1400 46 48 47 1600 4344 43 2000 40 41 42

Table 5 shows the average particle size of the low volatile matter andfractured particles as a function of work zone temperature for threedifferent coal particle sizes used as a feed material for the process.FIG. 15 shows this data as a graph.

Different coal particle sizes were used as the feed material for thethermal fracture and microcarbon separation process of coal particles.As seen in Table 5 and FIG. 15 , at low work zone temperatures (1000° C.or less) the particles are different sizes. When larger coal particlesare used for the process, the fractured particle size is also largerthan when smaller particles are used for the process. Once the work zonetemperature exceeds 1200° C., then the fractured particle size is aboutthe same for this work zone temperature regardless of the size of thecoal particle used for the process. There is also the expected trend ofsmaller particle size with increasing work zone temperature.

The data shown in Table 5 and FIG. 15 were collected for low volatilematter and thermally fractured particles made using 35 wt. % volatilematter bituminous coal as the feed material for the thermal fraction andmicrocarbon separation process. Low volatile matter and thermallyfractured particles made from feedstocks of lignite, bituminous,sub-bituminous, and anthracite all showed similar particle size trendsfor the temperature range shown above.

Example 8

TABLE 6 Work Zone Temperature Sub- (° C.) Bituminous bituminous Lignite600 15 18 20 800 10 14 15 1000 6 7 9 1200 3 4 5 1400 1 1.5 2 1600 0.70.8 0.9 2000 0.5 0.6 0.7

Table 6 shows wt. % volatile matter of low volatile matter and fracturedparticles as a function of work zone temperature when using bituminouscoal, sub-bituminous coal, or lignite coal for the process. FIG. 16shows this data as a graph.

Three different types of dry coal (<2 wt. % moisture) were used as thefeedstock in the thermal fracture and microcarbon separation of coalparticles: bituminous coal, sub-bituminous coal, and lignite. All threecoals had a particle size between 1 mm and 0.3 mm. Volatile matter was35 wt. % for the bituminous coal, 45 wt. % for the sub-bituminous coal,and 55 wt. % for the lignite coal.

The low volatile matter and fractured particles have about the samevolatile matter across the work zone temperatures tested. The highervolatile matter lignite had the highest volatile matter as expected. Ata work zone temperature of about 1200° C. and above, the volatile matterof the low volatile matter and fractured particles is about the same fora given temperature regardless of which coal particle type was used.

Further Discussion

All ranks of coal, e.g., anthracite, bituminous, sub-bituminous, andlignite can be used as a feedstock in the rapid thermal fracture andmicrocarbon separation process. Anthracite is a higher rank coal withvolatile matter usually below 10%. More low volatile matter andfractured particles would be expected at all temperatures compared toother coals. The coal tar or microparticles produced would be less thanall other coals. Both sub-bituminous coal and lignite coal have highvolatile matter, sometimes reaching as high as 55%. Using these highvolatile matter coals as a feedstock to the rapid thermal fracture andmicrocarbon separation process would produces less low volatile matterand fractured particles than coals with lower volatile matter. The coaltar or microparticles produced would be greater than other coals becauseof the higher volatile matter in the sub-bituminous or lignite feed coalparticles. Similar results as discussed for the high volatile mattermetallurgical grade met coal for the processes depicted in FIGS. 9, 10,11, 12, and 13 are expected.

Dry biomass such as waste crop clippings, wood chips, sawdust, manure,sewage, hay, etc. could be used as a feedstock into the rapid thermalfracture and microparticle separation process. Similar results asdiscussed for the high volatile matter metallurgical grade met coal forthe processes depicted in FIGS. 9, 10, 11, 12, and 13 are expected.

Waste plastics, waste rubbers, waste polymers, all discarded plastics,rubbers, and polymers, all recyclable plastics, rubbers, and polymerscould be used as a dry feedstock into the rapid thermal fracture andmicroparticle separation process. Similar results as discussed for thehigh volatile matter metallurgical grade met coal for the processesdepicted in FIGS. 9, 10, 11, 12 , and 13 are expected.

Summary and Observations

Coal is a low-grade fuel because of impurities. Coal has entrained orentrapped mineral matter impurities. It also has elemental impurities aspart of the carbon molecular structure or carbon matrix, in particularsulfur, nitrogen, and oxygen, and hydrogen. Sulfur, nitrogen and oxygendecrease the energy content of the coal.

When subjecting dry coal particles to high temperature thermal treatment(>800° C.) in the absence of oxygen, thermal fracture or thermalshattering occurs upon the production of coal tar vapor from the coalparticles, resulting in a 10× size reduction without the mechanicalcosts and challenges of conventional milling and comminution.

Reducing particle size at very high temperature (>1200° C.), coalparticles are shattered, destructive distillation produces coal tarvapors and organic gases. Carbonization occurs such that N, S, O areremoved from the carbon matrix of the low volatile matter and fracturedparticles. Coal tar vapor and organic gases are instantly carbonized toreform solid microcarbon particles. Both the low volatile matter andfractured particles and the microcarbon particles are coal-derived, yetthey are no longer coal. The low volatile matter and fractured particlesare greater than 10× smaller than the feedstock coal particles, are veryporous because of the loss of volatile matter in the shattering process,and have different CHNSO than the original coal particles and areusually conductive. The microcarbon particles are usually less than 1micron in diameter, do not have a size or shape similar to coal at all,have no entrained mineral matter, have different CHNSO content than theoriginal coal particles, and are usually conductive. Coal is neverconductive. Also, these two solid coal derived particles are producednearly instantaneously at the same time in the same high temperaturework zone.

Coal is an unstable material. It has a complex molecular structureconsisting of linked macromolecules. Upon heating above about 200° C. to250° C., coal tar vapor is produced because bonds are broken creatingsmaller molecules that vaporize at these temperatures. As thetemperature exceeds 250° C. up to about 700° C., bond breaking producescoal vapor. Above about 700° C., little coal tar is produced. Instead,sulfur, nitrogen, hydrogen, and oxygen are lost from the molecularstructure or carbon matrix until only pure carbon is left. Small organicgases such as methane, ethane, and propane may also be produced attemperatures greater than about 700° C. to 900° C. The processes oflosing organic gases and S, N, H, and O at higher temperatures untilpure carbon remains is called carbonization. Generally, pure carbon canbe produced at temperatures above about 1000° C. A carbon material thathas been exposed to temperatures greater than about 700° C. to 800° C.where the volatile matter content is less than 10% and the carboncontent is greater than 90% is stable for a wide range of temperatures.One meaning of stable is that coal tar vapor no longer evolves from thecarbon material at high temperatures.

There are two main ways coal is used, both of which are at hightemperature. (1) coal is burned or exposed to heat in the presence ofoxygen to produce heat. The flame temperature is around 1900° C. Thefirst thing that happens during burning is that new coal particles areheated by already burned and burning coal particles. Coal tar vapor isproduced as the coal heats up above about 250° C. The coal tar vaporinteracts with oxygen in the vapor phase and burns from the vapor phase.The leftover mass that did not enter the vapor phase is still a solid.The solid coal interacts with oxygen and burns until gone. It takes alonger period of time for complete burnout or consumption of the solidthan the vapor. Boilers and burners must be designed to ensure both thevapor and solid are completely burned. There is not a standard burnerdesign because coal doesn't have a standard response to high temperatureprocessing. (2) Coal is heated in the absence of oxygen to produce coke.Coke furnaces slowly increase in temperature from ambient temperature toabout 1000° C. Upon heating the coal, coal tar vapor is produced astemperatures exceed 200° C. to 250° C. Since there is no oxygen, thecoal tar vapor exits the furnace unburned. The solid that remainscross-links into a stable, porous bulk solid with high carbon content,forming the material known as coke. After exiting the coking furnace,the coal tar vapor may be burned or condensed and collected.

Coal is unstable when heated to temperatures above 250° C. to 300° C.whether in the presence or absence of oxygen. Above 250° C. to 300° C.,coal tar vapor and organic gases are emitted or produced.

Coal does not have a consistent response across all temperature ranges.The result of the variable response of coal to different temperatures isthat a standard high temperature process/equipment cannot be developedfor all coal. Instead, the process and equipment must be tuned to thecoal used. Furthermore, sulfur, nitrogen, and oxygen are a part of themolecular structure of coal. These elements are undesirable or notadvantageous in most uses of coal. There does not exist a process thateconomically stabilizes coal across a broad temperature range that alsoreduces and removes sulfur, nitrogen, and oxygen.

We demonstrate a process that can use any coal with a variable responseto high temperature thermal treatment in the presence or absence ofoxygen and stabilize it into two different coal-derived solid particlesthat are thermally stable. In this disclosure, the larger coal derivedparticles have been called low volatile matter and fractured particles.In this disclosure, the smaller coal derived particles have been calledmicrocarbon particles.

Potential uses for the low volatile matter and fractured particlesinclude high carbon content pulverized coal injection (PCI) material,stabilized fuel for coal fired power plant, mass produced activatedcarbon for water filtration, and mass-produced activated carbon soiladditive to enhance ion holding capacity and therefore fertility ofsoil.

Potential used for microcarbon particles include high carbon contentmaterial as part of a PCI blend, filler and strengthener for plasticsand rubbers, fuel for clean burning distributive microturbines, andmass-produced material for battery electrodes.

The described embodiments and examples are all to be considered in everyrespect as illustrative only, and not as being restrictive. The scope ofthe invention is, therefore, indicated by the appended claims, ratherthan by the foregoing description. All changes that come within themeaning and range of equivalency of the claims are to be embraced withintheir scope.

1. A process for fracturing coal particles comprising exposing coalparticles to a high temperature, oxygen-depleted work zone for a timeperiod less than 2 seconds to cause volatile matter within the coalparticles to vaporize and fracture the coal particles and to producecoal-derived low volatile matter and fractured particles, wherein thework zone has a temperature in the range from 1000° C. to 2000° C.,wherein the high temperature, oxygen-depleted work zone contains lessthan 1.5% oxygen.
 2. The process for fracturing coal particles accordingto claim 1, wherein the coal particles are exposed to the hightemperature, oxygen-depleted work zone for a time period less than 1second.
 3. The process for fracturing coal particles according to claim1, wherein the coal particles are exposed to the high temperature,oxygen-depleted work zone for a time period less than 0.3 second.
 4. Theprocess for fracturing coal particles according to claim 1, wherein thecoal-derived low volatile matter and fractured particles have a diameterthat is 5 times or more smaller than the original coal particles, avolatile matter content less than 10% by weight, a carbon contentgreater than 90% by weight, a sulfur content less than 1% by weight, anitrogen content less than 1% by weight.
 5. The process for fracturingcoal particles according to claim 1, wherein the coal particles have aparticle size less than 10 mm.
 6. The process for fracturing coalparticles according to claim 1, wherein the coal-derived low volatilematter and fractured particles have an average particle size less than200 μm.
 7. The process for fracturing coal particles according to claim1, wherein the vaporized volatile matter form coal-derived microcarbonparticles within the work zone.
 8. The process for fracturing coalparticles according to claim 1, wherein the high temperature,oxygen-depleted work zone is obtained from combustion gas exiting apulse combustor or pulse jet engine.
 9. The process for fracturing coalparticles according to claim 1, wherein the high temperature,oxygen-depleted work zone contains less than 1.0% oxygen.
 10. Theprocess for fracturing coal particles according to claim 1, wherein thecoal particles are unprocessed and have a given particle size, volatilematter content, sulfur content, and nitrogen content on an ash-freebasis, and wherein the coal-derived low volatile matter and fracturedparticles are characterized by a reduction of two or more of particlesize, volatile matter content, sulfur content, and nitrogen content onan ash-free basis compared to the unprocessed coal particles.
 11. Athermal mill for reducing the particle size of coal particlescomprising: a work zone having a coal particle inlet and a fracturedparticle outlet; a source of high temperature, oxygen-depleted gasconnected to the work zone to provide the work zone with an operatingtemperature in the range from 1000° C. to 2000° C., wherein the hightemperature, oxygen-depleted work zone contains less than 1.5% oxygen;and a source of moving gas to entrain and convey coal particles via thecoal particle inlet into the work zone for a time period less than 2seconds to cause volatile matter within the coal particles to vaporizeand fracture the coal particles, thereby forming coal-derived lowvolatile matter and fractured particles, and to entrain and convey thecoal-derived low volatile matter and fractured particles via thefractured particle outlet.
 12. The thermal mill according to claim 11,further comprising a cyclone to recover the coal-derived low volatileand fractured particles.
 13. The thermal mill according to claim 11,wherein the coal particles have a particle size less than 10 mm.
 14. Thethermal mill according to claim 13, wherein the coal-derived lowvolatile and fractured particles have an average particle size less than200 μm.
 15. The thermal mill according to claim 11, wherein the coalparticles are exposed to the work zone for a time period less than 1second.
 16. A coal-derived solid material obtained by exposingunprocessed coal particles having a given particle size, volatile mattercontent, carbon content, sulfur content, nitrogen content, and entrainedmineral matter content to an oxygen depleted gas at a temperaturegreater than 1000° C. for a time period less than 2 seconds, wherein theresulting coal-derived solid material is characterized by a reduction ofone or more of particle size, volatile matter content, carbon content,sulfur content, nitrogen content, and entrained mineral matter contentcompared to the unprocessed coal particles.
 17. The coal-derived solidmaterial according to claim 16, having a sulfur content less than 50% ofthe sulfur content of the unprocessed coal particles.
 18. Thecoal-derived solid material according to claim 16, having a volatilematter content less than 10% by weight.
 19. The coal-derived solidmaterial according to claim 16, having an average particle size lessthan 50% of the average particle size of the unprocessed coal particles.20. The coal-derived solid material according to claim 16, having areduced diameter compared to the unprocessed coal particles, a volatilematter content less than 10% by weight, a carbon content greater than90% by weight, a sulfur content less than 1% by weight, and a nitrogencontent less than 1.5% by weight.
 21. The coal-derived solid materialaccording to claim 16, consisting of coal-derived low volatile matterand fractured particles.
 22. The coal-derived solid material accordingto claim 16, consisting of coal-derived microcarbon particles.